'use strict'

// App env options prefix regex
const APP_ENV = /^APP_/i

const fs    = require('fs')
const path  = require('path')
const paths = require('./paths')

// Make sure that including paths.js after env.js will read .env variables.
delete require.cache[require.resolve('./paths')]

const NODE_ENV = process.env.NODE_ENV
if (!NODE_ENV) {
	throw new Error(
		'The NODE_ENV environment variable is required but was not specified.'
	)
}

// https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
var dotenvFiles = [
	`${paths.dotenv}.${NODE_ENV}.local`,
	`${paths.dotenv}.${NODE_ENV}`,

	// Don't include `.env.local` for `test` environment
	// since normally you expect tests to produce the same
	// results for everyone
	NODE_ENV !== 'test' && `${paths.dotenv}.local`,
	paths.dotenv,
].filter(Boolean)

// Load environment variables from .env* files. Suppress warnings using silent
// if this file is missing. dotenv will never modify any environment variables
// that have already been set.
// https://github.com/motdotla/dotenv
dotenvFiles.forEach(dotenvFile => {
	if (fs.existsSync(dotenvFile)) {
		require('dotenv').config({
			path: dotenvFile,
		})
	}
})

// We support resolving modules according to `NODE_PATH`.
// This lets you use absolute paths in imports inside large monorepos:
// https://github.com/facebookincubator/create-react-app/issues/253.
// It works similar to `NODE_PATH` in Node itself:
// https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
// Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
// Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
// https://github.com/facebookincubator/create-react-app/issues/1023#issuecomment-265344421
// We also resolve them to make sure all tools using them work consistently.
const appDirectory = fs.realpathSync(process.cwd())
process.env.NODE_PATH = (process.env.NODE_PATH || '')
  .split(path.delimiter)
  .filter(folder => folder && !path.isAbsolute(folder))
  .map(folder => path.resolve(appDirectory, folder))
  .join(path.delimiter)

// Grab NODE_ENV and APP_ENV_* environment variables and prepare them to be
// injected into the application via DefinePlugin in Webpack configuration.
function getClientEnvironment(publicUrl) {
	const raw = Object.keys(process.env).filter(key => APP_ENV.test(key)).reduce((env, key) => {
		env[key] = process.env[key]
		return env
	},
		{
			// Useful for determining whether we’re running in production mode.
			// Most importantly, it switches React into the correct mode.
			NODE_ENV: process.env.NODE_ENV || 'development',
			// Useful for resolving the correct path to static assets in `public`.
			// For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
			// This should only be used as an escape hatch. Normally you would put
			// images into the `src` and `import` them in code to get their paths.
			PUBLIC_URL: publicUrl,
		}
	)

	// Stringify all values so we can feed into Webpack DefinePlugin
	const stringified = {
		'process.env': Object.keys(raw).reduce((env, key) => {
			env[key] = JSON.stringify(raw[key])
			return env
		},{}),
	}

	return { raw, stringified }
}

module.exports = getClientEnvironment
